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ice- 3 FIP7909 UNITED STATES PATENT OEErcE.

JOHN B. BERNADOU, OF THE UXITED STA'llIS NAVY.

SMOKELESS POWDER AND PROCESS OF MAKING SAME.

SPECIFICATION forming part of Letters Patent No. 8,586, dated July 20, 1897.

Application filed February 4, 1897. Serial No. 622,011. (No specimens.)

To to whom it may concern:

Be it known that I, JOHN ll. BERNADOU, lieutenant United-States Navy, a citizen of the United States, stationed at United States Naval Torpedo Station at the city of Newport, in the county of Newport and State of Rhode Island, have invented certain new and useful Improvements in Smokeless Powders and Their Methods of Manufacture; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

My invention relates to improvements in the manufacture of smokeless powders, and especially in those smokeless powdersin which the principal ingredient is nitrocellulose or a mixture of nitrocelluloses.

From numerous experiments I have determined that an efficient colloid powderone that produces a minimum amount of smoke and that develops high velocities accompanied with relatively low bore-pressuresshould possess the following requisites:

First. Maximum toughness. The tougher the colloid material of which the strips or grains are composed, the less brittle that it is, the more plastic that it is, and the more that it is capable of resisting the tendency to fly into small fragments upon the application of v a sudden violent blow then the more progressive will be the manner of combustion of the colloid and the greater will be the developed velocity corresponding to a given bore-pressure.

Second. A content of oxygen sufficient to consume its .carbon into wholly gaseous-products. In the case of colloids prepared from nitrocelluloses not containing enough'oxygen to consume their own carbon the unconsumed carbon is either blown into the air as smoke or else is deposited upon the sides of the bore.

Third. The lowest content of oxygen consistent with the fulfilment of the abovenamed condition. The higher the nitration of the nitrocellulose from which the colloid powder is prepared the greater will be the heat and energy developed by the combustion of the same, the more rapid will be the development of pressure by the powder, and the brusquer the powder-that is, the greater the developed pressure corresponding to a given velocity.

I have discovered that the method commonly followed in the preparation of nitrocelluloses for explosive uses (wherein the nitrocellulose is, for the purpose of developing its stability, (A) boiled in water, (I3) treated with alkali in solution, or (O) boiled in an alkaline solution) does not produce the form of nitrocellulose capable of conversion into the most efficient colloid explosive for the reasons that, first, the treatment in alkali affects the nitrocellulose so that its nitration is reduced from what it would have been had it not been exposed to the action of alkali and so that the ether-alcohol colloid prepared from the nitrocellulose thus treated develops certain qualities of brittleness that militate against its efficiency as a progressive explosive; second, the exposure of the nitrocellulose to boiling or to a temperature above 66 centigrade aifects the nitrocellulose so that its ether-ah trogen, about 12.45 per cent. and correspond ing from the known formula for cellulose (O H O to a composition O l-I (N 09 0 may be prepared in the following manner: The form of cellulose preferably employed for nitrating is cotton, which is cleaned, picked, dried at temperatures between 93 centigrade and centigrade, and cooled in air-tight receptacles, in which it is kept until time of nitration. The acids employed for nitration are a mixture of two parts by weight of nitric acid of density 1.-l2 at 20 centigrade and three parts by weight of sulf uric acid of density 1.83 at 20 centigrade. The mixture quarter.

is allowed to cool to atmospheric temperature before use. Should acids of other strengths be used to make the mixture, water is to .be added to the mixed acids in such proportions as to bring the specific gravity of the mixture at the temperature of 20 centigrade to the specific gravityghat the mixture of acids of strengths as above defined would have at that temperature.

The limits of range of strength of acids with which the nitrocellulose may be prepared is for the nitric acid from 1.415 to 1.425 specific gravity at 20 ccntigrade and for the sulfuric-acid from about 1.825 to 1.835 at 20 centigrade.

The croc-ks used are preferably those commonly employed for' the nitration of guncotton, of hard glazed earthenware or semiporcelain and are about ten inches in height and eight inches in diameter. Into each of them is poured about twenty pounds in weight of mixed acids; which fills them to within about three inches of their tops. Into the acids about one pound of dried cotton is worked with iron or other suitable forks. As soon as the cotton is thoroughly worked into the acids an inner glazed lid or other suitable device is placed over it in such a manner as tokeep the whole of the nitrating-cotton below. the surface of the acid mixture. This precaution is to prevent firing upon the subsequent heating of the acids. A heavy overlapping cover is now placed over the top of the crock, and the crock thus covered is stood very nearly up to its edge in the immersionwater, maintained at a temperature of about centigrade. The crock is allowed to remain in this water for about an hour and a It will be found that the temperature of the nitrating mass will rise to about 45 centigrade and that when this temperature is attained a portion of it begins to go into solution. The crock should be removed from time to time and its contents stirred to secure a uniform temperature throughout the mass.

The type of crock employed and the amounts of acid and cotton taken may be modified as desired, providing the following conditions be fulfilled: that the amount of acid taken be in excess of that required to nitrate the cotton to its composition, as above shown,

and that the cotton be kept Wholly immersed in the acid, so that it does not come in contact with the air while the crock remains in the immersion-water.

When the contents of the crock have attained a temperature of from 42 to 46 cenplying a strip of blue litmus-paper to the wet nitrocotton the nitrocellulose is transferred directly to a pulper, where it is ground into iently neutralized by drawing off the pulpin g-water repeatedly. The nitrated product is now washed repeatedly by agitation with fresh water in the poacher. From four to seven washings will develop for it (when the sample is dried) a heat test of twenty minutes on exposure to a temperature of 65 centigrade. On withdrawal from the poacher the, nitrocellulose isdried with centrifugals until its content of water is reduced to between thirty and fifty per cent. The nitrocellulose is next washed and dehydrated in ethylic alcohol until its content of water is reduced by repeated washings to a desired percentage, low enough not to interfere with its direct incorporation into colloid powder. In this condition it is transferred directly to the mixer, where it is made into a colloid by the addition of the required amountbf the solvent used.

The washings in alcohol serve the important purpose of dissolving out of the nitrocellulose the unstable nitrocellulosesof low nitration that are present and that are soluble in ethylic alcohol. It will be found as the result of the dehydrating process that the st bility of the nitrocellulose is raised from twenty minutes at 65 centigrade to thirty minutes at that temperature.

The material obtained under the above process is a particular form of nitrocellulose, possessing the desired content of nitrogen, about 12.45 per cent. It is distinguished as a particular form of nitrocellulose by the facts, first, that it is soluble in a mixture of three parts by weight of ethylic alcohol and one part by weight of ethylie ether; that it is insoluble in ethyl alcohol alone. In ether-alcohol it colloids readily into a mass that is capable of being readily formed into grains or strips of uniform dimensions, which when dried possess a high degree of toughness as compared with other forms of colloid nitrocellulose prepared under processes in which the steps of boiling and exposure to action of alkali occur. 1

The nitrocellulose thus formed may be converted directly into smokeless powder, as above described, or it may be mixed with military guncotton or with one or more ni-' trates of metallic base, or both military guncotton and such nitrate or nitrates of metallic,

base may be added,if desired, and the mass may be then formed into grains of uniform dimensions or of such other dimensions as may be preferred.

second,

IIC

. By the term military guncotton I mean tion, or 12.45 per cent. nitrogen and corresponding to the formula O l-I (NO O the said process consisting in lm1H61SlDg hhG cellulose in. a mixture of nitric and sulfuric acids and bringingthe same to a temperature of between 42 centigrade and 46 eentigrade, then freeing the product from an excess of uncombined acids by washing and pulping in water at a temperature below 71 Centigrade, dehydrating and washing in an excess of ethylic alcohol, and then drying substantially as described.

2. The process for the manufacture of an improved form of nitrocellulose colloid from nitrocellulose of substantially uniform nitration, or 12.45 per cent. nitrogen, and correspondin g to the formula C H (NO O which process consists in immersing cellulose in a mixture of nitric and sulfuric acids and bringing the mass to a temperature of between 42 centigrade and 46 centigrade, freeing the product from excess of uncombined acid by washing and pulping in water at a temperature below 71 centigrade, dehydrating and washing in an excess of alcohol, and then colloiding the mass, substantially as described.

3. The process for the manufacture of an improved form of nitrocellulose colloid from nitrocellulose of substantially uniform nitration, or 12.45 per cent. nitrogen, and corresponding to the formula O H (NO O whichprocess consists in immersing cellulose in a mixture of nitric and sulfuric acids and bringing the mass to a temperature of between 42 centigrade and 46 centigrade, freeing the product from excess of uncombinedacid by washing and pulping in water at a temperature below 71 centigrade, dehydrating and washing in an excess of alcohol, and then 001-, loiding the product in a mixture of ethyl al= nitrocellulose of substantially uniform nitration, or 12.45 per cent. nitrogen and corresponding to the formula O H (NO O in the form of strips or grains, substantially as set forth.

6. .As an explosive cement or toughening agentin progressive powders,an ether-alcohol colloid of nitrocellulose of substantially uniform nitration, or 12.45 per cent. nitrogen and corresponding to the form ula C H (NO O into which nitrates of metallic base are incorporated.

7. As an explosive cement or toughening agent in progressive powders,an ether-alcohol colloid of nitrocellulose of substantially uniform nitration or 12.45 per cent. nitrogen, corresponding to the formula O H (NO O into which nitrates of metallic base and insoluble nitrocellulose are incorporated.

8. An ether-alcohol colloid of nitrocellulose I 

